Vent flange/smoker core (single scans)

(Left) A knob from a piece of an active flange recovered by the submersible ALVIN from the Endeavour Main Field vent site on the Juan de Fuca Ridge, off the coast of Washington. Sample dimension is approximately 10 cm wide. Flanges are ledges up to 5 meters long composed of mixtures of sulfide, sulfate, and silica that protrude from the sides of active seafloor vent structures. A 10-cm-deep pool of high temperature fluid (336°C) was pooled beneath this flange at the time of sampling. The upper surface of the flange was covered with living organisms; low temperature (~10°C, versus ~2°C for the surrounding seawater) fluids percolated through this upper surface. The purpose of scanning the sample is to image the 3-dimensional structure of dense sulfide-rich layers, less dense sulfate-rich layers, and pore space within the sample. The sulfate present is anhydrite (CaSO4) which is undersaturated in seawater at temperatures less than ~150 to 180°C. The anhydrite-dominated areas are extremely fragile, and it is difficult to sub-sample the flange without destroying the textures, making CT data particularly valuable. (Sample provided by Dr. John Delaney, University of Washington, and Dr. Margaret Tivey, Woods Hole Oceanographic Institute). (Right) Image of a 1" (25 mm) core from a deep-sea black smoker. The objective of this study was to estimate proportions of sulfide versus quartz and/or anhydrite versus pore space. CT data provides a detailed picture of internal structure, channel morphology, and pore space distribution in the smoker material. This in turn allows examination of fluid flow paths and more rigorous quantification of thermal conductivity by taking mineral connectivity into account. (Sample provided by Dr. Margaret Tivey, Woods Hole Oceanographic Institute).

©1998-2003